xtrema2

After car warms up when turning left rear slips and u hear a clunking noise.I've been told to try changing diff oil and put in a posi additive in hopes that someone neglected to do so.If that did'nt work have clutches changed in rear.What is the best method to siphon out old oil ? Local parts store is pushing a plastic push pump is their a better way ?

Tampa Jerry

I bought a siphon pump at my local auto store. It looks like a full sized grease gun. There is a hose at one end that goes into the liquid you want to transfer. The other end has a handle that you pull and that holds the liquid in the barrel. It can be a bit messy but it works. I would add a bottle of the GM oil and add two bottles of the posi additive and top off with GM oil. Next, drive the car again in tight circles. That should do it. Jerry

Ron Miller

Not sure what you mean by a plastic push pump, but a lot of service stations used to have a metal vacuum pump that looks a lot like one of the old style metal grease guns, only without the pump handle and with the grease nozzle end replaced by a flexible tube. They "suck" when you pull out the stem in the end of the pump/gun, the one you'd normally pull out in a grease gun to load the cartridge. Sadly, not all stations have such an item now.

I had the local station change my differential fluid and asked about the pump I'm referring to above, but was told they always just unbolt slightly the rear cover on a differential to drain the oil. Not so easily done on a Corvette with the Diff bolted to the frame crossmember.

So, I went out to the local parts house, bought a pump like I'm referring to above for about $10.00 and turned it over to the local service station for use on my car, and as a "gift" after they were through with mine.

Skip forward to this year, I've since acquired a 4-post lift, got ready to do the other car. So, I went down to the station, "borrowed" their vacuum pump, did mine and returned the pump. I'd rather they keep up with it than me.

That or something similar might be an option for you!!



(Jerry beat me to the draw, same thing with a lot less verbiage!) lol

nassau66427

I used a piece of clear tubing. Snaked it to the bottom of the case, started a siphon the old fashioned way, and let it drain overnight.

Ron Miller

That'll work. But I'm never sure if my siphon hose is at the bottom of the diff or not, mine always tends to want to curl. With the suction gun, I can try 3-4 times until I'm sure I have most of it out.

Whatever Works!

Hitch

Mighty vac works great...



I got mine at Autozone for about 40 bucks, works great for bleeding brakes, checking vac cans, installing vac cans etc...

Midyrman

Worked for me. I would suggest that once you have rear case nearly drained to reposition the hose a couple of times to be sure you got all the old oil out.

Mike Geary

Check out the Topsider Multi-purpose vacuum pump.

Can't beat it for diff's, tranny's, lawnmowers, etc. Anything without a bottom drain plug.

xtrema2

Thanks to all who responded

LT1driver

used the above ideas, to messy...I drilled 1/8 hole in bottom of case and installed plug and just drain like you would do oil, faster, no mess. done in on many of the vettes I have owned over the years.

Kensmith

Just siphon out enough to put some posi fluid in unless you think it needs changing. I used a turkey baster with clear plastic tubing over the end I had left over from when I was bleeding the brakes. Once you get the turkey baster to start the suction, remove it and gravity will continue the siphon in the tubing. You can suck with your mouth but I have had bad tastes from doing that.

Ron Miller

I think I'll stick with the full sized grease gun type siphon. I can't imagine how my turkey would taste the following November!!

(Hey Ken, just pulling your chain!! )

Bill Irwin

Ah Turkey is a bit greasy to begin with........ Don't worry bout it. Bill

Kerrmudgeon

Ray, do yourself a favour and drive in tight figure 8's, maybe 2 times in each direction before you change the fluid. No sense putting a bunch of debris from the discs into fresh oil. Drain plug hole makes sense but I'd do it when it's on the bench, some clearances are fairly tight inside so you want it in the right spot, and you don't want drill filings getting in.

P.S. make sure it's after a fair drive to get the oil hot before you suck it out.

silverslashstreak

I have fixed a few sticking clutches like this although it is a pain in the rear it beats a rebuild.

Pull as much of the old fluid out that you can.
Replace it with automatic transmission fluid.
Drive slowly to a parking lot and drive in a tight circle to the right 10 times and then to the left 10 times.
Then backup in a circle to the right 10 times and backup to the left 10 times.
Repeat this quit a few times or until your neck gets tired, not fast just at a steady slow speed.

Then back home and replace atf with differential lube and two bottles of the special Positrac additive.

Still running the last one I fixed. Probably has another 75000 miles on it with no problems.

Jeff
Jeff

54greg

I used the tranny fluid trick on a 94 that would not stop chattering. Filled with amsoil and their additive. Solved the problem

xtrema2

Thanks to all who responded,so far so good

Frankie the Fink

Gotta admit....I've been around a while and that's a new one on me...certainly worth a shot! Wish I had known about it when I had my posi Mustangs with clutch packs.